Kevzara Drug Interactions: What to Avoid and What to Tell Your Doctor

If you're taking Kevzara (sarilumab), it's critical to know how it interacts with other medications. Kevzara affects the CYP450 enzyme system—the liver's drug processing machinery—which means it can change how your body metabolizes many other drugs. Some interactions are serious enough to require close monitoring or dose adjustments. Here's what you need to know in 2026.

How Kevzara Affects Drug Metabolism (The CYP450 Connection)

IL-6—the protein that Kevzara blocks—has a side effect on the liver: elevated IL-6 suppresses the CYP450 enzyme system, which is responsible for metabolizing many medications. This means that in people with high IL-6 (like untreated RA patients), drugs metabolized by CYP450 enzymes are broken down more slowly, leading to higher drug levels in the blood.

When Kevzara blocks IL-6, it restores CYP450 enzyme activity. This means drugs metabolized by CYP450 will now be processed faster—potentially lowering their blood levels and reducing their effectiveness. Conversely, if you stop Kevzara, CYP450 activity decreases and drug levels can rise.

Key rule: When starting or stopping Kevzara, your doctor needs to check and possibly adjust the doses of any drugs you take that are metabolized by CYP450 enzymes.

Specific Drug Interactions to Know About

1. Live Vaccines — CONTRAINDICATED

Do not receive any live vaccines while taking Kevzara. Live vaccines include: MMR (measles/mumps/rubella), live attenuated influenza (nasal spray FluMist), Zostavax (live shingles vaccine), yellow fever vaccine, varicella (chickenpox), and oral typhoid vaccine. The concern is that the live virus in these vaccines could cause an active infection in an immunosuppressed patient. This is an absolute contraindication—not just a precaution.

2. Other Biologic DMARDs — CONTRAINDICATED

Avoid combining Kevzara with other biologic DMARDs. This includes:

TNF inhibitors: adalimumab (Humira), etanercept (Enbrel), infliximab (Remicade), certolizumab, golimumab

IL-1 receptor antagonists: anakinra (Kineret)

Anti-CD20 antibodies: rituximab (Rituxan)

JAK inhibitors: baricitinib (Olumiant), upadacitinib (Rinvoq — contraindicated), tofacitinib (Xeljanz)

T-cell costimulation blockers: abatacept (Orencia)

Combining Kevzara with these drugs would result in excessive immunosuppression, dramatically increasing the risk of serious and potentially fatal infections. These combinations have not been studied for safety and are to be avoided.

3. Warfarin (Blood Thinner) — Monitor Closely

Warfarin (Coumadin) is metabolized by CYP2C9, which is affected by IL-6 levels. When you start Kevzara, CYP450 enzyme activity increases, and warfarin may be metabolized faster—potentially lowering your INR and increasing clotting risk. When you stop Kevzara, the opposite can happen—warfarin levels may rise, increasing bleeding risk.

Your anticoagulation clinic or prescriber should monitor your INR closely when you start or stop Kevzara, and adjust your warfarin dose as needed.

4. Statins (Cholesterol Medications) — Dose Adjustment May Be Needed

Statins such as simvastatin, lovastatin, and atorvastatin are metabolized by CYP3A4. When you start Kevzara and CYP3A4 activity increases, statin levels may drop. A clinical study showed that simvastatin acid levels decreased by 36–45% when sarilumab was given. This could reduce the effectiveness of your cholesterol medication. Your doctor may need to adjust your statin dose or monitor lipid levels more closely.

5. Oral Contraceptives — Backup Contraception May Be Needed

Birth control pills, patches, and vaginal rings are hormonal contraceptives that contain estrogen or progesterone—both metabolized by CYP3A4. Because Kevzara may increase CYP3A4 activity, it can potentially reduce blood levels of these hormones, reducing the effectiveness of your birth control and risking unintended pregnancy.

Your doctor may recommend using a backup contraception method (such as a barrier method) while on Kevzara. Discuss this with your rheumatologist or gynecologist, particularly if you're relying solely on hormonal birth control.

6. Theophylline (Asthma/COPD Medication) — Monitor Drug Levels

Theophylline, used for asthma and COPD, has a narrow therapeutic window—meaning the difference between therapeutic and toxic doses is small. Because theophylline is metabolized by CYP1A2 (which is affected by IL-6 levels), starting or stopping Kevzara can change theophylline blood levels. Your doctor should monitor theophylline levels when you make changes to your Kevzara therapy.

7. NSAIDs and Corticosteroids — Increased GI Perforation Risk

While not a CYP450 interaction, taking NSAIDs (ibuprofen, naproxen, etc.) or corticosteroids (prednisone) simultaneously with Kevzara increases the risk of gastrointestinal perforation—a potentially life-threatening tear in the stomach or intestines. Many RA and PMR patients take these drugs, so be sure to inform your rheumatologist about all your pain and anti-inflammatory medications.

What to Tell Every Doctor You See

Always carry a complete medication list and tell every healthcare provider you see—including dentists, urgent care clinicians, and other specialists—that you are taking Kevzara. The CYP450 interaction potential means that any new prescription could be affected. For more safety information, read our guide on Kevzara side effects.